The epigraph to Paul Davies’s mind-stretching book is a quote from Arthur C Clarke: “Sometimes I think we’re alone in the universe, and sometimes I think we’re not. In either case the idea is quite staggering.” This neatly encapsulates the whole business of the search for extraterrestrial life. Whatever the truth turns out to be, it will be awe-inspiring.

Davies is an excellent popular-science writer, as well as a physicist and cosmologist so eminent that he even has an asteroid named after him (formerly known as 1992OG). He is also chairman of the Search for Extraterrestrial Intelligence Post-Detection Taskgroup, which sounds like something out of Doctor Who, but is deadly serious. He is keenly aware of “the mismatch between the futility of the human condition and the brooding majesty of the cosmos”, and The Eerie Silence makes for a magnificent cosmic tour d’horizon of what we know, and what we might yet encounter out there, in the apparent emptiness of deep space.

[I trust that in the book itself the apparent mismatch is countered by an argument that there is, paradoxically, an extraordinary mathematical and possibly proportional systemic match in many ways between the structures of a human body and brain and the observable universe. If enlarged sufficiently, we are mostly space and the number of cells in our bodies are 'astronomical' as is pointed out two paras below. Furthemore, it is we who inagine and perform any brooding.]

Has the hunt for extraterrestrial life found anything yet? There has been confusion here. In 1996, Bill Clinton announced that Nasa had found life on Mars — but then Clinton claimed a number of things that turned out to be not strictly true. Life has not been found on other moons or planets yet, no. But almost all astrobiologists feel it’s only a matter of time. Water is far more common elsewhere than we thought. It’s even present on the moon, and there’s probably more water on Europa, a moon of Jupiter, than in all the earth’s oceans. And where there’s water, there’s life.

However, what most of us mean by ET is intelligent life. This is another kettle of fish altogether. Self-aware intelligence may just be a weird and rare aberration. Even on the home planet, life has always been and always will be, essentially, bacterial. Both you and I can reasonably be described as a flourishing bacterial colony, wrapped around with a thin layer of usefully protective human tissue. [A point that cannot be emphasised too often, but not with any a deprecatory or demeaning implication for human values.] You’re about 10 quadrillion human cells and 100 quadrillion bacterial cells: the kind of blackly comic revelation about ourselves that modern science throws up all the time.

So when we do discover the first extraterrestrial life-form, it won’t be an eerie and thrilling close encounter of the third kind. It’ll be some amoeba on Europa, or a bit of blue-green algae on Titan. For all but the specialist, it might be rather a letdown.

The chances for intelligent life look very different. Davies entertainingly dismisses the encounters with aliens as reported by certain Americans, 40m of whom have seen UFOs. Most of these sightings, he explains politely, are probably Venus rising in the morning, which to the uninitiated might look like a gleaming flying saucer. Then there’s the regrettable “banality of the aliens’ putative agenda, which seems to consist of grubbing around in fields and meadows, chasing cows or aircraft or cars like bored teenagers, and abducting humans for Nazi-style experiments”.

“It could be that life is common, but intelligence is rare,” says Davies. And it may be rare not because it doesn’t evolve in the first place, but because when it does, it soon destroys itself. [This is an important consideration. Darwin and Cuvier (Evolution and Extiction theories) both rule in the science of evolutionary outcomes, just as, I maintain, Gamov-Einstein-Hubble and Fred Hoyle's theories on aspects of universal origins, once seen as contradictory, will be see as both alive and well when we have the multidimensional model.] Look at our own “intelligent civilisation”, currently making its own continuance unlikely not just through global warming, but in 1,001 other interesting and creative ways. Advanced civilisations may be so energy-greedy and inherently unstable, modifying the environment around them so violently, thinks Davies, that they inevitably collapse after only a few centuries. For us to communicate with another, therefore, the timing has to be right. Imagine a town of 100 houses, he suggests, but where each house only lights up for 10 seconds a night. To enable communication, two must light up simultaneously. The chances are virtually nil. [Davies is being too optimistic! Lighting up simultaneously will not achieve comunication when what we mean is knowing a signal has been received. The most we could hope for would be evidence of a transmission from a civilisation alive many, many years ago. 'Simultaneous' is not what we think in the universe of space-time relativity.]

Such a grim explanation would explain “the eerie silence” out there perfectly. Davies likens this to the obvious answer to Stephen Hawking’s famous question: Where are all the time travellers from the future? There aren’t any, points out Davies, because time travel into the past is not and never will be possible. Travel into the future might be ­feasible, as Einstein showed. But nothing in the laws of physics will allow for us going backwards. [Paradoxically time-travel to the past is exactly what we do have, whether we like it or not. The world we experience is entirely in the past. We see the Sun of 8 minutes ago, and to look further back in the past all we have to do is look. On our own planet, we have the records of the past all around us. As for travel into the future, you are doing it now. What we cannot do is visit the future by jumping out of the sequence of local thermodynamics except in our imagination, or visit the past in practicality (that means touching it). To touch something implies presence and then it is the present.  But since both these methods are available, why should we wish to confuse matters by trying to misapply them? Our sanity is logic dependent. I am not ruling out superluminary entanglement but that is for another day.]

Even allowing for the remote chance of alien intelligence, how do we know they won’t be just really unpleasant, like Douglas Adams’s thuggish Vogons, with their hideous personal habits and rubbish poetry? Should we really be trying to contact aliens at all, advertising our presence to the universe like wide-eyed, smiley children trying to make friends with a crocodile? [Good point, and here is the answer: if beings as stupid and unpleasant as the Vogons find themselves in charge of advanced technology, the evolutionary equations suggested by Darwin and Cuvier and should take care of them. If we happened to meet them before they had destroyed themselves or got lost in space we would indeed be astronomically unlucky!]

Another point is that any alien intelligence, no matter how advanced, could still only communicate at the speed of light. Aliens 1,000 light years away — in cosmic terms, virtually next door — would see earth as it was in AD1010, when we’d only just invented clockwork. If 10,000 years away, they would be just in time to catch a few enterprising Iraqis starting to grow wheat. Would they bother to make friends with such useless primitives?

This raises more humiliating possibilities. Perhaps plenty of alien civilisations are well aware of our existence, having monitored us for millennia. But they have yet to see any reason to call us up. They might find us sickeningly ugly, spectacularly stupid, dangerously violent, or just dull. [Even more likely, if they were at a more advanced stage than us they would know full well that we must solve our own problems. A truth I have tried with little success to point out in other contexts.]

Finally, Davies asks us to imagine what an alien intelligence might look like. Little green men with weedy legs, bug eyes and alopecia, no: ‘“post-biological intelligence” would long since have dispensed with the heartache and the thousand natural shocks that flesh is heir to. Our alien visitor would be more like a self-designed supercomputer, immune to death and decay. Its thought processes, however, would still be limited by the speed of light. Even if it was a brain the size of a planet, says Davies, it would simultaneously be “dazzlingly brilliant but relatively slow-witted”. [Here I disagree totally with Davies. They are far more likely to be creatures who have reached a proper knowledge of the nature of sentient, fleshly existence and the way it renews itself and evolves. They would have a far more advanced understanding of death, of life as an individual and life as a community. I am not talking Borg, by the way, very far from it.]

And how would it spend its self-created eternity? “Some commentators have suggested that super-advanced intellects of this sort would spend most of their time proving ever more subtle mathematical theorems.” So there you are. Our long-awaited encounter with ET might be with a very clever but slow-witted quantum computer that spends its limitless aeons solving very complex Sudoku puzzles. [Yes, now you are getting to the point where you will begin to understand you are talking nonsense and I have proved to my satisfaction that whatever else creation is about, it is not nonsense. That is why I found HHGTTG such an important book. It is in exploring the nonsense that results from taking our simplistic ideas to logical conclusions that we can emerge from the womb.]

On the lookout

Astronomers at the Search for Extraterrestrial Intelligence have been scanning the skies for signals since April 1960, with only a few hoaxes and false alarms to show for it. So far they have checked on several thousand stars within 100 light years. Given that the universe* contains 400 billion stars spread over 100,000 light years, their lack of success is not so surprising. [*As was pointed out by an online reader of this review, Christopher Hart made a slip here. For 'universe' read 'our Milky Way galaxy'. The universe may contain 500 billion galaxies of such approximate size!

The answer to the question 'Are we Alone' is simple if by 'alone' we mean what we say when a person is alone as in "We die alone" by David Howarth. It is simple if what we mean is 'are we on our own here'? The answer is yes even if the whole universe is breeding human civilisations by the million. However,  the links with the universal past are not what people suppose, and the entanglements through what we call the past are not what people suppose. The very fabric of space-time which defines the values of inertial mass is past-dependent and, in a multidimensional universe, though that past is inaccessible in what we call practicality, reality and materiality, it's power is not necessarily so. The phenomenon of resonance which plays a vital role in communication at a distance, is not necessarily confined to conventional electrodynamics and thermodynamics or the conventional media. There are virtual possibilites. Our existence can make possible a greater existence. When we get an understanding of that, our worries about being alone may fall away. I guess I will have to actually read this book now just to see if Paul Davies has reached the same conclusion. Sounds as if not yet.... but nearly?]

The Eerie Silence: Are We Alone in the Universe? by Paul Davies
Allen Lane £20 pp255